Middletown, Connecticut has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 5.3 °C (low) to 15.9 °C (high). Annual precipitation averages 1305.8 Millimeters. Middletown is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -6.8 °C | 2.5 °C | 96.27 mm |
| February | -6.1 °C | 3.8 °C | 83.82 mm |
| March | -1.8 °C | 8.2 °C | 113.28 mm |
| April | 3.8 °C | 15.2 °C | 107.44 mm |
| May | 9.3 °C | 21.1 °C | 96.01 mm |
| June | 14.6 °C | 25.8 °C | 125.22 mm |
| July | 17.7 °C | 28.8 °C | 106.17 mm |
| August | 16.8 °C | 27.9 °C | 108.2 mm |
| September | 12.7 °C | 24 °C | 116.08 mm |
| October | 6.2 °C | 17.3 °C | 135.38 mm |
| November | 0.8 °C | 11.1 °C | 101.35 mm |
| December | -3.7 °C | 5.5 °C | 116.59 mm |
| Annual | 5.3 °C | 15.9 °C | 1305.81 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6b : -20.6°C to -17.8°C |
| Plant Hardiness Zone - 2012 | Zone 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |